JP3679250B2 - Engine valve and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, in a manufacturing process of an engine valve, an engine valves Contact and manufacturing method thereof can be omitted polishing step of the outer periphery of the bulging portion of the engine valve.
[0002]
[Prior art]
Conventionally, engine valves have been used as engine components. This engine valve is composed of a bulging portion whose one end is formed in an umbrella shape and a shaft portion formed integrally with the bulging portion.
[0003]
Here, an outline of the manufacturing process of the engine valve will be described.
[0004]
First, the rod-shaped member cut into a predetermined length by the cutting means is upset-molded through, for example, an electric upsetter or the like, whereby one end portion of the rod-shaped member is heated to form a substantially spherical heating portion. The heating unit obtained by the upset molding is subjected to press processing via a press device, and after the predetermined heat treatment is performed on the press-formed body, various polishing processes are performed.
[0005]
That is, after the outer peripheral portion of the shaft portion is subjected to rough polishing, the shaft portion is cut into a predetermined length, and further, rough polishing is performed on the inclined inner wall surface of the bulging portion. Subsequently, after polishing the shaft portion again, polishing processing is performed on the outer peripheral portion of the bulging portion.
[0006]
Furthermore, after an annular groove is formed on one end side of the shaft portion, the shaft portion is subjected to various polishing processes such as finish polishing to finally complete the engine valve as a product.
[0007]
By the way, since the rod-shaped member is made of a difficult-to-mold material such as heat-resistant steel or heat-resistant superalloy, a high current and a high pressure are required when performing the upset molding, and heating with stable roundness is performed. There is a problem that it is difficult to form a part.
[0008]
In addition, if the roundness of the heating part of the molded body obtained by the upset molding is not stable, there is a variation in the heating temperature for the heating part of the upset molded body heated by the heating means when performing press working in the next step. It may occur and the flowability of the meat during press molding may be deteriorated, resulting in a lacking portion. This is because the heating temperature in the heating part becomes non-uniform due to the difference in the separation distance between the maximum diameter part and the minimum diameter part of the heating part and the heating means. In order to avoid the occurrence of the lacking portion, it is necessary to apply a high press molding load in the press work, and there is a problem that burrs are inevitably generated with the high load molding.
[0009]
Therefore, in order to solve the above-mentioned various problems, in the prior art, the outer diameter size of the outer peripheral portion of the bulging portion, which is a part where burrs are generated, is previously slightly larger than the completed size including the allowance portion. The dimensional accuracy of the outer peripheral portion of the bulging portion 2 is obtained by setting and polishing the outer peripheral portion of the bulging portion 2 with a grindstone 1 as shown in FIG.
[0010]
For example, the mold apparatus shown in FIG. 12 has a first lower die 3 and a second lower die 4, and a cavity 5 is formed in the second lower die 4. The dimension D includes the machining allowance part 6 (see FIG. 13), and is set larger by ΔF than the outer diameter dimension E of the bulging part 7 of the engine valve which is a finished product. Therefore, as shown in FIG. 13, the molded body 8 obtained by the mold apparatus is larger than the outer diameter dimension E of the bulging portion 7 of the engine valve which is a finished product by ΔF which is the allowance portion 6. It is formed.
[0011]
[Problems to be solved by the invention]
By the way, in the manufacturing method of the engine valve which concerns on a prior art, since a high precision and high intensity | strength are requested | required with respect to the bulging part and axial part which have an umbrella shape, very many manufacturing processes are required.
[0012]
In particular, the polishing process is divided into a number of polishing processes because various polishing processes are required depending on the polishing site or the size of abrasive grains to be polished, and there is a demand for simplifying the polishing process as much as possible.
[0013]
In addition, the roundness of the heating part of the molded body obtained by the upset molding, that is, the dimensional difference between the maximum diameter part and the minimum diameter part of the heating part is stabilized as close to zero as possible, and press molding is performed. There is another demand to suppress the generation of burrs due to uneven thickness by suppressing the molding load.
[0014]
The present invention has been made in consideration of the various requirements described above, omits the polishing step of the outer peripheral portion of the bulging portion, simplifies the manufacturing process, and roundness of the heating portion of the upset molded body. was stable and an object to provide an engine valves Contact and its manufacturing method capable of suppressing the press forming load.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is an engine valve comprising a bulge portion having an umbrella shape and a shaft portion formed integrally with the bulge portion,
Completing the heating part of the upset molded body, which has a rod-shaped body material made of heat-resistant steel with a Ni content of 10 wt% or more and 30 wt% or less, and is formed by heating and expanding one end of the rod-shaped body Forming the engine valve, which is the finished product, only by pressing with a die having a cavity formed in the same dimension as the diameter of the bulging part of the engine valve, which is a product,
The heating portion of the upset molded body is formed into an elliptical shape when viewed from above by upset molding, and the dimensional difference between the maximum diameter portion (X) and the minimum diameter portion (Y) of the elliptical shape is 0.03 mm or more and 0.10 mm. and wherein the Rukoto such from below.
[0017]
Further, the present invention is an engine valve manufacturing method comprising a bulging portion having an umbrella shape and a shaft portion formed integrally with the bulging portion,
A step of bulging one end of a rod-shaped body made of heat-resistant steel having a Ni content of 10 wt% or more and 30 wt% or less by upset molding, and forming an upset molded body having an elliptical heating section when viewed from above ;
The heating portion of the upset molded body obtained by the process, Tsu by the applying only pressing by the die having formed in the same size as the diameter of the bulging portion of the engine valve is a finished cavity Te, and forming an outer peripheral portion of the bulged portion of the engine valve is a finished product,
Have a,
The heating portion of the upset moldings, dimensional difference between the maximum diameter portion (X) and the minimum diameter portion (Y) and is characterized Rukoto such from the following 0.10mm or 0.03 mm.
[0018]
In the present invention, first, an upset molded body having an elliptical heating section as viewed from above is formed by upsetting one end of a rod-shaped body made of heat-resistant steel having a Ni content of 10 wt% to 30 wt% by upset molding. Subsequently, the heating part of the upset molded body is subjected only to pressing with a die having a cavity formed in the same dimension as the diameter of the bulging part of the engine valve as a finished product. The outer peripheral part of the bulging part of the engine valve, which is a finished product, is formed. In this case, the heating part of the upset molded body may have a dimensional difference between the maximum diameter part (X) and the minimum diameter part (Y) set to 0.03 mm or more and 0.10 mm or less. According to the present invention, the roundness of the heating portion can be stably obtained by upset molding, and the outer peripheral portion of the bulging portion of the engine valve is formed only by pressing . As a result, it is not necessary to polish the outer peripheral portion of the bulging portion, and the manufacturing process is simplified.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The engine valve manufacturing method according to the present invention will be described in detail below with reference to the accompanying drawings by giving preferred embodiments in connection with an apparatus for carrying out the method.
[0020]
FIG. 1 is a schematic configuration diagram of an upset molding apparatus that performs upset molding in an engine valve manufacturing method.
[0021]
The upset molding apparatus 10 includes a pressing cylinder (not shown) provided with a piston rod 14 that abuts on one end of a rod-shaped body 12 that is a molding material and presses the rod-shaped body 12 upward, A forging table 16 that is in contact with the other end and provided so as to be movable up and down, a clamp cylinder (not shown) provided with a pair of arms 18a and 18b sandwiching the rod-like body 12, and a pair of arms 18a and 18b, respectively. It comprises a pair of electrodes 20a and 20b which are provided and heat the rod-shaped body 12 by energization.
[0022]
FIG. 7 shows a mold apparatus for performing press molding in the method for manufacturing an engine valve.
[0023]
The mold apparatus 22 is fixed to a base portion (not shown), and includes a first lower die 26 formed with a through hole 24 through which a knockout pin (not shown) is inserted along the vertical direction of the center portion. The second lower die 32 is inserted into the hole portion 28 of the first lower die 26 and the cavity 30 is formed in the central portion, and the cavity 30 is inserted into the cavity 30 under the driving action of a lifting means (not shown). And an upper punch 34 that pressurizes the workpiece.
[0024]
In this case, the inner diameter dimension S of the cavity 30 formed in the second lower die 32 is set to be the same or substantially the same as the outer diameter dimension T of the bulging portion 38 of the engine valve 36 which is the finished product shown in FIG. ing.
[0025]
The upset molding apparatus 10 and the mold apparatus 22 for carrying out the engine valve manufacturing method according to the present invention are basically configured as described above. Next, the function and effect will be described.
[0026]
First, the process of performing upset molding on the rod-shaped body 12 that is a molding material will be described. As shown in FIG. 1, after setting the rod-shaped body 12 between the piston rod 14 of the pressing cylinder and the forging table 16, the pair of arms 18a and 18b are brought close to each other under the driving action of a clamp cylinder (not shown). Then, the electrodes 20a and 20b provided on the pair of arms 18a and 18b are clamped in a state of being in contact with the rod-shaped body 12 (see FIG. 2).
[0027]
In a state where the rod-like body 12 is clamped by the pair of arms 18a and 18b, the electrodes 20a and 20b are energized to heat the rod-like body 12, and the piston rod 14 is displaced in the direction of the arrow under the driving action of the pressing cylinder. Then, the bar is pressed upward (see FIG. 3).
[0028]
In this case, as shown in FIG. 4, the bar-shaped body 12 is pressed upward by the piston rod 14 of the pressing cylinder at the same time while raising the forge table 16 via a lifting means (not shown).
[0029]
Therefore, under the heating action by the electrodes 20a and 20b and the pressing action by the pressing cylinder, one end portion of the rod-like body 12 contacting the forge table 16 expands to form a substantially spherical heating section 40 ( (See FIG. 4). After the heating unit 40 having a desired shape is formed, the energization of the electrodes 20a and 20b is stopped, and the clamp cylinder is driven to separate the arms 18a and 18b from the rod-shaped body 12, thereby removing an unillustrated taking-out means. Then, the upset molded body 42 is taken out (see FIGS. 5 and 6). In this way, upset molding is completed.
[0030]
Here, the roundness of the heating unit 40 when upset molding is performed on a plurality of molding materials by the upset molding apparatus 10 will be described.
[0031]
Molding materials include material A (martensitic heat-resistant alloy), material B (approximately 30% by weight Ni-containing austenitic heat-resistant alloy), material C (approximately 40% by weight Ni-containing austenitic heat-resistant alloy), material D (approximately 60%). Five types were used: weight% Ni-containing austenitic heat-resistant alloy) and material E (substantially 75 weight% Ni-containing austenitic heat-resistant alloy). Further, the maximum diameter portion of the heating portion 40 of the upset molded body 42 obtained by upset molding for the five types of molding materials is X, the minimum diameter portion is Y, and the minimum diameter portion Y is subtracted from the maximum diameter portion X. The value (XY) is shown on the vertical axis.
[0032]
In this case, in the prior art, a material in which the Ni content of the heat-resistant steel material that is the rod-shaped body 12 is more than 30% and 60% or less is used, and the difference between the maximum diameter portion X and the minimum diameter portion Y is , 0.15 to 0.25 mm. For this reason, in order to eliminate the lack of thickness at the time of press molding, the load becomes relatively high and burrs are easily generated.
[0033]
In view of this, it has been found from experiments that burrs and undercuts due to uneven thickness occur when the difference between the maximum diameter portion X and the minimum diameter portion Y of the heating unit 40 exceeds 0.10 mm.
[0034]
On the other hand, when the Ni content of the heat-resistant steel material is less than 10% by weight, the difference between the maximum diameter part X and the minimum diameter part Y is further reduced and the roundness of the heating part 40 is improved, but the durability is deteriorated. Is concerned.
[0035]
Therefore, the Ni content of the heat-resistant steel material that is the rod-shaped body 12 is preferably 10% by weight or more and 30% by weight or less, and examples thereof include molding materials such as the material A and the material B.
[0036]
Further, as described above, regarding the difference between the maximum diameter portion X and the minimum diameter portion Y of the upset molded heating portion 40, if the thickness exceeds 0.10 mm, burrs and thinning due to uneven thickness tend to occur. On the other hand, if the thickness is less than 0.03 mm, the durability may deteriorate.
[0037]
Therefore, the difference between the maximum diameter portion X and the minimum diameter portion Y of the upset molded heating portion is preferably 0.03 mm or more and 0.10 mm or less.
[0038]
As described above, in the present embodiment, by using a molding material having a Ni content of 10% by weight or more and 30% by weight or less, the roundness can be improved and the roundness can be improved without deteriorating the durability. It is possible to obtain an upset molded heating unit 40 having the properties.
[0039]
Next, press molding is performed on the upset molded body 42 obtained by upset molding by the mold apparatus 22 shown in FIG.
[0040]
That is, in the state where the upset molded body 42 is set in the cavity 30 formed in the second lower die 32 and the heating unit 40 is heated to a predetermined temperature by a heating unit (not shown), it is under the driving action of a lifting unit (not shown). The upset molded body 42 is pressurized through the upper die punch 34. As a result, the heating part 40 of the upset molded body 42 is plastically deformed corresponding to the shape of the cavity 30 to obtain a press molded body.
[0041]
In this case, the inner diameter dimension S of the cavity 30 formed in the second lower die 32 is the same as the outer diameter dimension T of the bulging portion 38 of the engine valve 36, which is a finished product, without adding a machining allowance portion. Or since it is set substantially the same, it is not necessary to cut the machining allowance part by post-processing. In other words, the outer diameter dimension T of the bulging portion 38 of the engine valve 36 that is a finished product is formed only by plastic working (pressing) on the heating portion 40 of the upset molded body 42. Therefore, in the present embodiment, in the manufacturing process of the engine valve 36, the polishing process for cutting the machining allowance portion can be omitted.
[0042]
Further, since the roundness of the heating part 40 of the upset molded body 42 is ensured with high accuracy, the heating part 40 can be uniformly heated by the heating means when press molding, and the meat flow during press molding It is possible to prevent the occurrence of burrs and missing parts due to uneven thickness.
[0043]
Furthermore, as shown in FIG. 10, the press molding load of the material B against the material D was reduced by about 10%, and the press molding load of the material A against the material D was reduced by about 16%. Therefore, generation of burrs can be avoided by suppressing the press molding load during press molding.
[0044]
In addition, the engine valve as a finished product is obtained by performing various processes with respect to the said press-molded body.
[0045]
Thus, the polishing of the outer peripheral surface of the bulging portion 38 can be omitted by post-processing due to the synergistic effect of improving the roundness of the heating unit 40 in upset molding and increasing the mold accuracy in press molding. . As a result, the manufacturing process can be simplified and the manufacturing cost can be reduced.
[0046]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0047]
That is, the manufacturing process can be simplified by omitting the polishing process of the outer peripheral surface of the bulging portion of the engine valve.
[0048]
Moreover, the roundness of the heating part of an upset molded object can be stabilized, and the molding load at the time of plastic working can be suppressed. As a result, it is possible to prevent burrs from occurring at the bulging portion.
[0049]
Furthermore, by ensuring the roundness of the heated portion of the upset molded body, the plastic workpiece can be heated uniformly during plastic processing, and the flowability of the plastic during plastic processing is improved, resulting in uneven thickness. It is possible to prevent the occurrence of burrs and missing parts due to
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an upset molding apparatus that performs upset molding in an engine valve manufacturing method of the present invention.
2 is an operation explanatory view showing a state in which a pair of arms constituting the upset molding apparatus of FIG. 1 are approaching. FIG.
3 is an operation explanatory view showing a state in which a piston rod of a pressing cylinder constituting the upset molding apparatus of FIG. 1 is raised. FIG.
4 is an operation explanatory view showing a state in which a heating part is formed by energizing an electrode constituting the upset molding apparatus of FIG. 1 and pressurizing a rod-shaped body.
FIG. 5 is an operation explanatory view showing a state in which an arm and a piston rod are separated after a heating part is formed at one end of a rod-like body by an upset molding apparatus.
FIG. 6 is a front view of the upset molded body obtained by the upset molding apparatus.
FIG. 7 is a longitudinal cross-sectional configuration diagram of a mold apparatus that performs press molding in the method for manufacturing an engine valve of the present invention.
FIG. 8 is a front view of a bulging portion of an engine valve that is a finished product.
FIG. 9 is an explanatory view showing the relationship between the maximum diameter portion and the minimum diameter portion of the heating portion of an upset molded body obtained by upset molding a plurality of molding materials.
FIG. 10 is an explanatory diagram showing a press molding load at the time of press molding of a plurality of molding materials.
FIG. 11 is an explanatory view showing a process of removing a margin portion by grinding the outer peripheral surface of the bulging portion with a grindstone in the prior art.
FIG. 12 is a vertical cross-sectional configuration diagram of a mold apparatus in the prior art.
13 is a partially omitted front view of a molded body press-molded by the mold apparatus shown in FIG. 12. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Upset molding apparatus 12 ... Rod-shaped body 20a, 20b ... Electrode 22 ... Mold apparatus 26, 32 ... Lower die 30 ... Cavity 40 ... Heating part 42 ... Upset molded body

Claims (2)

An engine valve composed of a bulging portion having an umbrella shape and a shaft portion formed integrally with the bulging portion,
Completing the heating part of the upset molded body that has a rod-shaped material made of heat-resistant steel with a Ni content of 10 wt% or more and 30 wt% or less, and one end of the rod-shaped body is heated and expanded. Forming the engine valve, which is the finished product, only by pressing with a die having a cavity formed in the same dimension as the diameter of the bulging part of the engine valve, which is a product,
The heating portion of the upset molded body is formed into an elliptical shape when viewed from above by upset molding, and a dimensional difference between the maximum diameter portion (X) and the minimum diameter portion (Y) of the elliptical shape is 0.03 mm or more and 0.10 mm. engine valve, characterized in Rukoto such from below. An engine valve manufacturing method comprising an bulging portion having an umbrella shape and a shaft portion formed integrally with the bulging portion,
A step of bulging one end of a rod-shaped body made of heat-resistant steel having a Ni content of 10 wt% or more and 30 wt% or less by upset molding, and forming an upset molded body having an elliptical heating section when viewed from above ;
The heating portion of the upset molded body obtained by the process, Tsu by the applying only pressing by the die having formed in the same size as the diameter of the bulging portion of the engine valve is a finished cavity Te, and forming an outer peripheral portion of the bulged portion of the engine valve is a finished product,
Have a,
The heating portion of the upset moldings, manufacturing method for an engine valve dimensional difference between the maximum diameter portion (X) and the minimum diameter portion (Y) is characterized Rukoto such from the following 0.10mm or 0.03 mm.

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